Recently released by the Bureau, the new IFDs are based on a more extensive database, with nearly 30 years’ additional rainfall data and data from 2,300 extra rainfall stations.

The new IFDs are part of a much wider revision of the Engineers Australia design handbook Australian Rainfall and Runoff: A Guide to Flood Estimation (AR&R). As part of the AR&R Revision, other inputs to design flood estimation are being revised including temporal patterns, areal reduction factors, losses and baseflow. These revisions will be delivered through Engineers Australia over the next two years.

The IFDs are used by engineers and hydrologists in the design of infrastructure including gutters, roofs, culverts, stormwater drains, flood mitigation levees, retarding basins and dams.